MONDAY, April 1, 2019 (HealthDay News) -- For pregnant women, a C-section carries a higher risk of severe complications than a vaginal delivery, particularly after age 35, a new study finds.

The researchers said that cesarean deliveries appear to cause an overall 80% increased risk of severe maternal complications when compared with vaginal delivery.

For women 35 or older, the risk from C-section is nearly triple that of normal delivery, and that risk leaps to fivefold if they undergo a C-section before labor has commenced, the investigators found.

For women younger than 35, there was about a 50% higher risk of severe complications.

"Cesarean can save lives in some situations. However, it is not a trivial procedure," said senior researcher Dr. Catherine Deneux-Tharaux, a research director with the Center for Epidemiology and Statistics at the Sorbonne in Paris. "It, in itself, carries risks of severe complications for the mother, mainly heavy bleeding, and should only be chosen as the delivery route when the risk-benefit balance has been discussed with the doctor."

C-section rates have soared over the past two decades in most developed countries, where more than one in every five women deliver by cesarean, the study authors said in background notes.

To see what risks these operations might pose to the mother, Deneux-Tharaux and her colleagues compared 1,444 women who experienced severe complications after delivery with 3,464 women who did not.

The proportion of C-section deliveries was twice as high among the women who experienced severe complications, compared with the healthy "control" group (36% versus 18%).

These complications included serious bleeding, seizures, pulmonary embolism (clots), stroke, organ dysfunctions or other problems that would require admission to an intensive care unit.

The increased risk of complications associated with C-sections remained even after the researchers took into account other factors that influence maternal health, and after they excluded women with pre-existing health conditions that could lead to complications.

Birth by C-section "carries risk of severe complications for the mother, both at short-term and for the next pregnancy," Deneux-Tharaux said. "In consequence, the mode of delivery should always be fully discussed by the women with the obstetrician or midwife, in order to avoid unnecessary procedures that carry risk."

However, moms-to-be shouldn't be alarmed by the report. To put things in perspective, Deneux-Tharaux noted that the risk of severe complications to women is about 1.5% across all modes of delivery. Overall risk remains low even with the increased risk that appears to accompany having a C-section delivery.

Dr. Joanne Stone, director of maternal-fetal medicine at Mount Sinai Health System in New York City, agreed.

"While this study shows an association with higher maternal morbidity with cesarean compared to vaginal delivery, the rates of such complications we know from other studies are still very low," Stone said.

Stone added that this study did not include long-term health problems that might come from an ill-advised vaginal birth involving a breech baby or multiple delivery.

Dr. Aaron Caughey, chair of obstetrics and gynecology at the OHSU School of Medicine in Portland, Ore., said that C-section inherently creates the possibility for complications because "you're making holes in people."

He said that "if you have a labor in a subsequent pregnancy after a prior C-section, your risk for a uterine rupture is about one in 200. The baseline risk of a uterine rupture is about one in 20,000. So by making a hole in someone's uterus, you increase the risk to subsequent pregnancies by about 100-fold. There's also nothing you can think of in health care that connotes a risk of 100-fold."

Caughey believes the increased C-section rate is largely being driven by inadequate monitors to track fetal health, combined with an abundance of caution among doctors and patients.

C-sections are necessary when the mother's or baby's life is at risk, but "we don't have great screening or diagnostic tools to tell us when to deliver babies in those settings, so it pushes us to do a lot more C-sections than are necessary, to prevent injury to babies and moms," Caughey said.

Fetal monitors are one example. "We have this inexact screening test, the fetal monitor, which tells us when babies are hypoxic [deprived of oxygen]," Caughey explained. "But babies experience hypoxia in essentially all labor."

Caughey is more doubtful when it comes to anecdotes of women choosing to undergo C-sections so they can better time their delivery.

"It's a thing that happens, there's no question, but I've given talks on C-section all over the country" and haven't come across many physicians with firsthand experience of such timed deliveries, Caughey said. "I don't really think it is nearly the driver that people thought it was. There's no evidence to support that."

The study was published April 1 in the CMAJ (Canadian Medical Association Journal).